LEACHING OF LIME AND FERTILIZERS FROM A RESEEDED UPLAND PASTURE ON A STAGNOGLEY SOIL IN MID-WALES

Concentrations of nutrients were measured in drainage water from a dra ined but otherwise unimproved area of Molinia grassland and from a sim ilar area following pasture improvement in Year 1 of the 4-year study. Application of lime and fertilisers to the improved area and reseedin g with a grass / white clover mixture had little effect on concentrati ons of nitrate and ammonium-N in drainage water except for one year wh en nitrate concentrations were increased to a maximum of 24 mg N l(-1) for a brief period following application of nitrogen fertiliser. Conc entrations of organic-N, potassium, phosphorus and calcium and the pH of water samples increased following pasture improvement and were cons istently greater than corresponding values for the Molinia area. By Ye ar 4 almost all of the potassium fertiliser applied to the reseeded ar ea in Years 1 and 2 had been leached. In the same period, about 12% of the phosphorus fertiliser and 24% of the lime application had been le ached.